Simplified installation captive panel fastener

ABSTRACT

A simplified captive panel fastener including a head, shank, a threaded outer end, and a centrally threaded opening at the outer end. Longitudinal slots extend along the outer end of the fastener to receive a retention washer with inwardly extending prongs. The method of mounting the fastener to its desired location and locking a retention washer and fastener in place is easily performed by employing a tool which disposes the threaded mating part, for example, a screw or bolt, into the central threaded opening of the outer end of the fastener. The head of the screw or bolt has radial extent sufficient to block the slots and prevent loss of the retention washer. Only a common screwdriver is used to mount the retention screw or bolt in the end of the fastener.

FIELD OF THE INVENTION

This invention relates to captive panel fasteners, which can be readilyreplaced without special tooling, for example in field maintenanceapplications.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,655,658 granted Apr. 7, 1987, inventor: B. Gulistan, isentitled Captive Panel Fastener. This patent discloses a fastener inwhich the abstract of the patent is useful in describing the fastener byway of background for the present invention. The abstract of the U.S.Pat. No. 5,655,658 will therefore be repeated here:

“A captive panel fastener includes a head, a shank and a threaded outerend, with slots extending longitudinally down through the threads towardthe outer end of the fastener. A relatively rigid and inflexibleretention washer is provided and this washer has inwardly extendingprongs that fit into the longitudinally extending slots on the fastener.The outer end of the fastener has a hole in it, and after the washer isin place a forming tool is employed to deform the outer end wall of theopening so that the wall is pushed outwardly to block the outer ends ofthe longitudinally extending slots, thereby holding the washer onto thefastener, and retaining it extending through a hole in a panel or thelike through which it may have been inserted. A small washer may beemployed at the end of the fastener between the ends of the slots andthe deformed extreme outer end of the fastener.”

On occasion, for example when the threads of the fastener are damaged,it would be desirable to replace the fastener at a field maintenancelocation. However, the installation of the captive fastener as describedabove requires a special forming tool, to deform the outer end wall ofthe fastener to hold the retention washer in place. It is impractical toprovide each field maintenance location with the required specialforming tool, and accordingly the aircraft or other equipment using thefastener is often used with the damaged fastener; and replacement is notaccomplished until the aircraft returns to a major maintenance locationwhere the forming tool is available.

SUMMARY OF THE INVENTION

In accordance with the present invention the need for a replacementfastener, which could be installed with minimal or basic tools, wasrecognized; and the new replacement threaded fastener, which is simpleto install, includes a head, a shank, and a threaded outer end withlongitudinally extending slots in the threads of the fastener. Inaddition, at the outer end of the fastener, a hole is provided and thishole is tapped to provide internal threads. Further, a small retentionscrew is mounted in the threaded hole; and the head of the screw extendsoutward to a sufficient extent to hold the retention washer in place. Inaddition, the small retention screw may be provided with ananti-vibration capability, such as a NY LOCK® insert or plastic spray onthe threads of either the retention screw or the threaded hole, so thatthe screw does not vibrate out of the assembly. Other knownanti-vibration arrangements may be used.

The principal advantages of the new design is that the replacementcaptive fastener may be readily installed in the field, as the onlytools required (if the threads on the original fastener are damaged forexample) would be a pair of pliers and a screw driver. Thus, the olddamaged fastener first is removed by bending the deformed end of the oldfastener with a pair of pliers, so that the retention washer may beremoved, thus freeing the damaged fastener for removal. The newreplacement captive fastener is then inserted in place without the smallretention screw, the retention washer is slid onto the grooved threadedmain fastener and then the retention screw is threaded into the end ofthe main fastener, locking the retention washer in place, and completingthe retrofit. Subsequently, a nut or other internally threaded matingfastener part is threaded onto the exposed threaded outer end of thecaptive fastener. Of course, every field maintenance location will atleast have pliers and screwdrivers available, so the retrofit may beaccomplished without the need for any special tooling such as theforming tool disclosed in the U.S. Pat. No. 4,655,658.

Other objects, features and advantages of the invention will becomeapparent from a consideration of the following detailed description andthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through a threaded fastener andretaining washer, illustrating the invention in the prior art (U.S. Pat.No. 4,655,658 to Bulent Gulistan).

FIG. 2 is a plan view of one example of a washer (U.S. Pat. No.4,655,658 to Gulistan).

FIG. 3 is a cross-sectional view of one end of the prior artconstruction, showing a washer with inwardly extending prongs fittinginto the longitudinally extended slots on the fastener (U.S. Pat. No.4,655,658 to Gulistan).

FIG. 4 is a partial cross-sectional view showing an alternativeembodiment of the prior art using a small supplemental washer (U.S. Pat.No. 4,655,658 to Gulistan).

FIG. 5 is a cross-sectional view through a threaded fastener andretaining washer, the outer end of the threaded fastener containing atapped central opening with internal threads for receiving of aretention screw, illustrative of the present invention.

FIG. 6 is a view of a floating nut assembly of the prior art (6A) andemployed with a fastener of the present invention (6B).

FIG. 7 is a partial cross-sectional view showing an alternativeembodiment of the invention using a small supplemental washer around anunthreaded region of the outer end of the fastener.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the specification describes particular embodiments of the presentinvention, those of ordinary skill can devise variations of the presentinvention without departing from the inventive concept.

Referring more particularly to the drawings, FIG. 1, 2, 3 and 4 areillustrative of the captive panel fasteners of the prior art of Gulistan'658. FIG. 1 shows a captive panel fastener 2 illustrating theprinciples of the prior art in U.S. Pat. No. 4,655,658 to Gulistan(Gulistan '658). The fastener 2 of Gulistan '658 has a head 10, a shank12 and an outer threaded end 14 with a central opening 20. The fastener2 has a plurality of slots 16 along the length of the fastener 2.Essentially, in Gulistan '658, once the fastener 2 is mounted in itsdesired location or panel 50 and the retention washer 24, with itsinwardly extending prongs 26 fitting into the longitudinal slots 16 (seeFIG. 2) of the fastener 2, is in place, the formable end wall 28 locatedat the tip of the outer end 18 of the fastener 2 is deformed using theplunger tool of Gulistan '658 (refer to FIG. 4 of that patent). Theaction of the plunger tool of Gulistan '658 is to bend and deform theformable end wall 28 of the fastener 2 such that it blocks the outerends 18 of the slots 16 and prevents the washer 24 from sliding off orfrom being removed from the fastener 2.

FIG. 2 shows an example of a washer 24 with inwardly extending prongs 26for fitting into the longitudinal slots 16 of the fastener 2. FIG. 3 isa cross-sectional view of the outer end 18 of the fastener 2 with awasher 24 in place.

FIG. 4 shows an alternative end configuration 6 of the fastener 2 ofFIG. 1, wherein the fastener including the threads 14-1, the opening20-1 and other features of the assembled captive panel fastener 2including a retention washer 24 are substantially as shown in FIGS. 1, 2and 3. However, in FIG. 4, the outermost end portion of the fastener18-1 is initially reduced to a diameter 52 slightly less than twice theradial distance from the center of the fastener 2 to the bottom of theslots 16-1. Also the outer diameter of the washer 54 in FIG. 4 and theoutwardly deformed formable end wall 28 in FIGS. 1 and 56 in FIG. 4 arepreferably about equal to the root of diameter of the threads to avoidinterference with a nut to be threaded to fastener 2.

FIG. 5 is illustrative of the present invention. The present inventionis simplified over the invention of Gulistan '658 because unlikeGulistan '658, which employed a special hand tool to deform the formableend wall 28 of the fastener 2, the present invention uses common, basictools (i.e. screwdriver) to accomplish the same goal. A special handtool to deform the formable end wall 28 of the fastener 2 is notpractical out in the field where common, basic tools such asscrewdrivers and pliers are readily available. Therefore, the presentinvention (see FIG. 5 description below) modifies the prior art ofGulistan '658 to incorporate the usage of these common tools to repairand/or install the fastener 8 and/or washer 72 and/or other captiveparts fastened by the captive panel fastener 8.

FIG. 5 shows a different captive panel fastener 8 from that of thefastener 2 in Gulistan '658 (see FIG. 1-4). The captive panel fastener 8of FIG. 5 does not require a special deforming device as that describedin Gulistan '658 (see FIG. 4). FIG. 5, shows the fastener 8 having ahead 60, a shank 62, a threaded outer end 64, longitudinal slots 66along the length of the threaded outer end 64 of the fastener 8, and acentral threaded opening 68. The fastener 8 is mounted through a panel100 and the retaining washer 72 is mounted with its inwardly extendingprongs 74 extending into the longitudinal slots 66 of the fastener 8.FIG. 5 also shows the threaded outer end 80 of the mating screw 76mounted into the central threaded opening 68 of the fastener 8. The head78 of the mating screw 76 blocks the slots 66, either directly orindirectly, and prevents the retention washer 72 from sliding off theouter end 70 of the fastener 8.

The captive panel fastener 8 of the present invention does not require aspecial deforming hand tool as that described Gulistan '658 (see FIG. 4)because the action of the plunger tool of Gulistan '658 was to bend anddeform the formable end wall 28 of the fastener 2 such that it blocksthe outer end portion 18 and prevents the washer 24 from sliding off orfrom being removed from the fastener 2. The present invention requiresno special deforming tool; rather the present invention relies on thehead 78 of the screw or bolt 76 to prevent the washer 72 from slidingoff the outer end portion 70 of the fastener 8.

FIG. 6 is a view of the known prior art floating nut assembly 4 (6A)employed with a fastener 8 type of the present invention (6B). FIGS. 6Aand 6B are placed together in the drawing to show a complete fastener.FIG. 6B is illustrative of the fastener 8 type of the present inventionsubstantially as shown in FIG. 5 but with a different head 60-1. FIG. 6Bshows a fastener 8-1 with its head 60-1, shank 62-1, threaded outer end64-1 and longitudinal slots 66-1. The central threaded opening 68 andthe threaded outer end 80 of the screw or bolt 76-1 are not shown. Thehead 78-1 of the threaded screw 76-1 is shown mounted into the centralthreaded opening 68 of the fastener 8-1 (details not shown in FIG. 6).The fastener 8-1 is mounted through a panel 100-1. The retaining washer72-1 with its inwardly extending prongs 74 (not shown in FIG. 6B) fitsinto the longitudinally extending slots 66-1 of the fastener 8-1substantially as shown in FIG. 5. In FIG. 6, the only tool that is usedto assemble the captive panel fastener 8-1 in its desired location is ascrewdriver to mount the screw 76-1 into the central threaded opening 68of the fastener 8-1. The threads 82 of the floating nut assembly 4 matewith the threads 64-1 at the outer end of the fastener 8-1 when thefastener 8-1 is finally tightened in place. Instead of the floating nutassembly 4, simple hexagonal nut with optional washers may be employed.

FIG. 7 shows an alternative end configuration 7 of the type of fastenershown in FIG. 5, wherein the fastener 8′ including the threads 64-1 andthe opening 80-1. Other features of the assembled captive panel fastener8′ including a retention washer 72 are substantially as shown in FIGS. 5and 6B. However, in FIG. 7, the outermost end portion 70-1 of thefastener 8′ is unthreaded and the small washer 84 blocks the slots 66-1and prevents the loss of the retention washer 72 (not shown in FIG. 7).The small washer 84 is held in place by the outer rim of the head 78-1of the screw 76-1.

In accordance with one aspect of the present invention, a method ofinstalling a captive panel fastener 8 of the present invention comprisesmounting the fastener 8 to its desired location. The retention washer72, with its inwardly extending prongs 74, is the slid onto the fastener8 and fits into the longitudinally extended slots 66 of the fastener 8.To block the washer 72 from sliding off the fastener 8, a threaded screwor bolt 76 is mounted into the central threaded opening 68 of thefastener 8 using a screwdriver. The screwdriver or tool employed dependson the head of the screw or bolt 78 mounted into the central threadedopening 68 of the fastener 8. The screw or bolt 76 contains a head 78with a radial extent sufficient to block the slots 66 and prevent lossof the retention washer 72. Note that only a screwdriver is used toassemble the captive panel fastener 8, whereas assembly of the fastener2 of the prior art requires a special deforming hand tool (see FIG. 4 ofGulistan '658).

In another aspect of the present invention, if in the field there is aneed to repair or replace a damaged fastener 8 of the type described inFIG. 5 and FIG. 6B, the damaged parts are easily replaced by unscrewingthe screw or bolt 76 from the central threaded opening 68 of the outerend 70 of the fastener 8. Removing the screw or bolt 76 allows both theretention washer 72 and the fastener 8 to be taken out of the panel 100.A new fastener 8 is mounted and another or the same retention washer 72is slid into place and prevented from sliding off by mounting a screw orbolt 76 as described above. In the case of a damaged fastener of thetype shown in FIG. 1, the fastener 2 may be removed using pliers to bendthe deformed end 28 inwardly, to permit removal of the retention washer24 and fastener 2; and a new captive panel fastener as shown in FIG. 5may be installed.

In another embodiment of the present invention, any threaded screw orbolt 76 can be installed and used to prevent both the fastener 8 and theretention washer 72 from sliding off. The head 78 of the screw or bolt76 should have a radial extent sufficient to block the slots 66 andprevent loss of the retention washer 72. Alternatively, the retentionscrew or bolt 76 may be a self-tapping screw or bolt.

In another aspect of the present invention, the fastener 8 including ahead 60, a shank 62, an externally threaded outer end 64 and a centrallythreaded opening 68 may be substantially as described in FIGS. 5 and 6B,except in this embodiment (see FIG. 7), the outer end portion 70-1 ofthe fastener 8 is unthreaded; and the head 78-1 of the retention screwor bolt 76-1 holds the washer 84 in place. Accordingly, the head 78-1 ofthe retention screw or bolt 76-1 may either directly block the lower endof the slots 66-1, or may do so indirectly by holding the washer 84 inplace.

Preferably, the retention screw or bolt 76 may be provided with ananti-vibration capability to avoid loosening in the presence ofvibration. For example, a NYLOCK® insert or another type of plasticinsert can be placed into the outer threaded end 80 of the screw or bolt76. Alternatively, a plastic spray can be sprayed on the threads ofeither the retention screw or bolt 76 or the threaded central opening68. Other known anti-vibration arrangements may also be used.

In conclusion, it is to be understood that the foregoing detaileddescription and accompanying drawings relate to one or more embodimentsof the invention. Other alternative arrangements may be employed withoutdeparting from the spirit and scope of the invention. Thus, for example,the number of slots 66 on the fastener 8 is variable and is dependent onthe fastener 8 application. In another example, the extent of theexternal 64 and internal threads 68 of the fastener 8 will also dependon the fastener 8 application. Further, the depth of the centralthreaded opening 68 of the outer end of the fastener 70 is at leastequal to or greater than the length of the threaded outer end 80 of thethreaded mating screw or bolt 76 that is installed. Also, any suitabletool can be used to remove a damaged captive panel fastener 8.Accordingly, it is to be understood the detailed description and thedrawings as set forth hereinabove are for illustrative purposes only,and do not constitute a limitation on the scope of the invention.

1. A captive panel fastener assembly comprising: a) a fastener having ahead, a shank, an externally threaded outer end and outer end portion;b) the shank having an outer diameter comparable to the outer diameterof the threaded portion of the fastener; c) the outer end of thefastener having a central opening, the opening having inwardly extendingthreads; d) the shank of the fastener including the threaded outer endhaving a plurality of longitudinally extending slots; e) a washer havinginwardly extending prongs for fitting into the longitudinally extendingslots, the washer being relatively inflexible; and f) a retention matingscrew or bolt having a head and a threaded outer end for mounting intothe threaded opening for blocking the outer ends of the slots andretaining the washer onto the fastener by preventing the washer prongsfrom sliding off the end of the fastener, and thereby holding thefastener captive in the desired location, the head of the retentionscrew being substantially within the profile of the extended pattern ofthe external threads of the fastener.
 2. The captive panel fastener asdefined in claim 1 wherein the shank has a diameter comparable to orgreater than the outer diameter of the threads of the fastener but lessthan the outer diameter of the washer.
 3. The captive panel fastener asdefined in claim 1 wherein the fastener has only two slots and whereinthe washer has two corresponding inwardly directed prongs.
 4. Thecaptive panel fastener as defined in claim 1 further comprising a smallwasher having an outer diameter extending beyond the bottom of theslots, the small washer being mounted on the outer end of the fastenerbetween the ends of the slots and the head of the retention screw ornut, wherein the head of the screw or bolt blocks the ends the slotsindirectly by holding the small washer in place.
 5. The captive panelfastener as defined in claim 1, wherein the depth of the centralthreaded opening is equal or greater than the length of the outerthreaded end of the retention mating screw or bolt mounted into theopening.
 6. The captive panel fastener as defined in claim 1 wherein thehead of the retention screw or bolt is extends outward to block outwardmovement of the prongs from the slots.
 7. The captive panel fastener asdefined in claim 1 wherein the retention screw or bolt is a self-tappingscrew or bolt.
 8. The captive panel fastener as defined in claim 1wherein the outer end portion of the fastener is unthreaded.
 9. Thecaptive panel fastener as defined in claim 1 wherein the retention screwor bolt has anti-vibrating properties.
 10. A captive panel fastenerassembly comprising: a) a fastener having a head, a shank including athreaded portion, and a central inwardly directed opening at the outerend thereof; b) the shank having a plurality of longitudinally extendingslots extending through the threads on the threaded portion of thefastener; e) a retention washer having inwardly extending prongs forfitting into the longitudinally extending slots; f) a retention screw orbolt having a head and a threaded outer end for mounting into theopening for blocking the outer ends of the slots and preventing theretention washer prongs from sliding off the end of the fastener, andthereby holding the fastener captive in the desired location.
 11. Thecaptive panel fastener as defined in claim 10 wherein the outer end ofthe fastener further comprises a small washer having an outer diameterextending beyond the bottom of the slots, the small washer being mountedon an unthreaded reduced diameter portion of the fastener between theends of the slots and the head of the retention screw or nut, whereinthe head of the screw or bolt blocks the ends the slots indirectly byholding the small washer in place.
 12. The captive panel fastener asdefined in claim 10 wherein the shank has a diameter comparable to orgreater than the outer diameter of the threads of the fastener.
 13. Thecaptive panel fastener as defined in claim 10 wherein the fastener hasonly two slots and wherein the washer has two corresponding inwardlydirected prongs.
 14. The captive panel fastener as defined in claim 10wherein clearance is provided at the outer end of the fastener, wherebythe washer may readily slide over the end of the fastener into theslots, prior to mounting of the retention screw or bolt into the centralthreaded opening.
 15. The captive panel fastener as defined in claim 10wherein the head of the retention screw or bolt is a self-tapping screwor bolt.
 16. The captive panel fastener as defined in claim 1 whereinthe retention screw or bolt has anti-vibration properties.
 17. A methodfor providing a captive panel fastener in place comprising the steps of:a) fabricating a fastener having a head and a threaded outer end, thethreaded outer end having a plurality of longitudinally extending slots,the outer end of the fastener having a central opening; b) mounting thefastener in the desired captive location; c) sliding a retention washerhaving inwardly extending prongs to fit closely into the longitudinallyextending slots with the washer extending around the fastener; and d)mounting a retention screw or bolt into the central threaded opening ofthe fastener, the retention screw or bolt having a head and externalthreads, the head having a diameter or outward extent to block theslots, but not interfere with threading a nut onto the fastener.
 18. Themethod of installing a captive panel fastener as defined in claim 17wherein the outer diameter of the head of the retention screw or bolthas a radial extent substantially greater than the bottom of the slots.19. The method of installing a captive panel fastener as defined inclaim 17 including the additional step of assembling a small washer toblock the ends of the slots prior to mounting the retention nut ofscrew, whereby mounting the screw or bolt blocks the ends of the slotsindirectly by holding the small washer in place.
 20. The method ofinstalling a captive panel fastener as defined in claim 17 including theadditional step of adding an anti-vibrating property to the retentionscrew or bolt.
 21. The method of claim 17 comprising the additional stepof threading a nut onto the threaded outer end of the fastener.